Toxicological responses of Cyprinus carpio exposed to the herbicide penoxsulam in rice field conditions.

Cyprinus carpio fish were exposed to penoxsulam (Ricer) in field conditions. The experiment in the rice field was carried out for 7, 21 and 72 days. Oxidative stress parameters and antioxidant profile were studied. The acetylcholinesterase (AChE) enzyme activity in the brain was increased after 7 days and reduced after 21 and 72 days of the experiment in the rice field. The AChE activity in muscle was reduced only after 72 days of exposure. Thiobarbituric acid-reactive species were increased in the liver, brain and muscle at 7 days of the trial, reduced at 21 days in the brain and unaltered after 72 days of exposure in muscle. However, an increase in this parameter in the brain and liver was observed. Liver glutathione S-transferase was reduced at 7 days, unchanged at 21 days and increased after 72 days of exposure. Catalase of the liver changed only in the second experimental period, when it was reduced. Liver protein carbonyl was reduced at 7 days and increased at 21 and 72 days of exposure. This study shows long-term effects of rice herbicide at environmentally relevant concentrations on toxicological parameters in different tissues (brain, muscle and liver) of Cyprinus carpio.